1. Field of the Invention
The present invention relates to: an optical element such as a lens; an optical element module cut from an optical element wafer module stacked with one or more optical element wafers having a plurality of lenses arranged in a two-dimensional pattern; an electronic element module where the optical element or the optical element module is modularized with an electronic element; and an electronic information device, such as a digital camera (e.g., a digital video camera or a digital still camera), an image input camera, a scanner, a facsimile machine, a personal digital assistant (PDA), a camera-equipped cell phone device, and a video telephone device using the electronic element module in an imaging section.
2. Description of the Related Art
For a conventional electronic information device having an imaging element and a light gathering lens element thereabove, such as a camera-equipped cell phone device and a personal digital assistant (PDA), further improvement in image quality as well as reduction in size and cost is demanded.
FIG. 9(a) is a perspective view of a conventional imaging lens unit disclosed in Patent Literature 1. FIG. 9(b) is a longitudinal cross-sectional view of the imaging lens unit in FIG. 9(a) along the line A-A′.
In FIGS. 9(a) and 9(b), in a conventional imaging lens unit 100, three lenses 101 to 103 are modularized by stacking sequentially from the top so that the light axes C align. The optical axes C of the three lenses 101 to 103 are aligned at the lens centers. Flange sections 101a to 103a are provided at the outer peripheral sections of the lenses 101 to 103, respectively, extending in a direction perpendicular to the optical axis C of the lenses 101 to 103. The flange sections 101a to 103a are not provided with protrusions or grooves for positioning. The flange sections 101a to 103a have a substantially square outline in a plane view, and comprises flange side surfaces 101b to 103b, respectively, aligned to the four outer wall planar surfaces mostly parallel to the optical axis C. Flange side surfaces 101b to 103b arranged in a same direction are disposed on the same planar surface along the direction of the optical axis C.
The lens 101 comprises a top lens surface 101c constituting a convex surface, and a bottom lens surface 101d constituting a concave surface. The lens 102 below the lens 101 comprises lens surfaces 102c and 102d constituting a convex surface for both the top and bottom surfaces. The lens 103 below the lens 102 comprises a top lens surface 103c constituting a concave surface, and a bottom lens surface 103d constituting a planar surface. The lens surface 101d side of the flange section 101a and the lens surface 102c side of the flange section 102a are in contact with each other. The lens surface 102d side of the flange section 102a and the lens surface 103c side of the flange section 103a are also in contact with one another.
FIG. 10 is a longitudinal cross-sectional view of a conventional imaging lens unit disclosed in Patent Literature 2.
In FIG. 10, a conventional imaging lens unit 200 is disposed by sequentially stacking four lenses 201 to 204 from the top along the optical axis C. For the four lenses 201 to 204, thick flanges 201a to 204a are provided, respectively, in the direction of the optical axis C at the outer peripheral section where there is no effect to the image formation functions. Among the side surfaces 201b and 201c through 204b and 204c of the flanges sections 201a to 204a of each lens, the side surface 201c of the lens 201 and the side surface 202b of the lens 202; the side surface 202c of the lens 202 and the side surface 203b of the lens 203; and the side surface 203c of the lens 203 and the side surface 204b of the lens 204 are each matched, and by attaching each matched surface, each lens 201 to 204 adheres in a state where the relative positions of each lens 201 to 204 are maintained.    Patent Literature 1: Japanese Laid-Open Publication No. 2004-088713    Patent Literature 2: Japanese Laid-Open Publication No. 62-153908